This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. The overall objective of this project is to assess the prevalence of a novel strain of HIV-2 group F in Sierra Leone. There has been one case of HIV-2-F in the United States documented that originated in the area of Sierra Leone that will be surveyed. The epidemiology and pathogenesis of HIV-2-F disease in human populations is unknown although available data suggest that it may have originated from a strain of SIV found in sooty mangabeys in Sierra Leone. Data on the prevalence of HIV-2 in human populations are presently lacking as the last survey was made 18 years ago and HIV-2-F may represent an emerging AIDS. To this end we will screen the human population in Northern Sierra Leone for prevalence of HIV-2-F infections. We will use antibody assays that have already been validated in this region. We will also use PCR based testing to screen samples that may be missed due to waning antibody titers.